r262443 - in /trunk/libstdc++-v3: ChangeLog inc...

[redi@gcc.gnu.org]

Author: redi
Date: Thu Jul  5 15:56:06 2018
New Revision: 262443

URL: https://gcc.gnu.org/viewcvs?rev=262443&root=gcc&view=rev
Log:
PR libstdc++/58265 implement LWG 2063 for COW strings

For COW strings the default constructor does not allocate when
_GLIBCXX_FULLY_DYNAMIC_STRING == 0, so can be noexcept. The move
constructor and swap do not allocate when the allocators are equal, so
add conditional noexcept using allocator_traits::is_always_equal.

	PR libstdc++/58265
	* include/bits/basic_string.h [!_GLIBCXX_USE_CXX11_ABI]
	[_GLIBCXX_FULLY_DYNAMIC_STRING==0] (basic_string::basic_string()):
	Add GLIBCXX_NOEXCEPT.
	(basic_string::operator=(basic_string&&)): Add _GLIBCXX_NOEXCEPT_IF
	to depend on the allocator's is_always_equal property (LWG 2063).
	(basic_string::swap(basic_string&)): Likewise.
	* include/bits/basic_string.tcc [!_GLIBCXX_USE_CXX11_ABI]
	(basic_string::swap(basic_string&)): Likewise.
	* testsuite/21_strings/basic_string/allocator/char/move_assign.cc:
	Check is_nothrow_move_assignable.
	* testsuite/21_strings/basic_string/allocator/wchar_t/move_assign.cc:
	Check is_nothrow_move_assignable.
	* testsuite/21_strings/basic_string/cons/char/
	noexcept_move_construct.cc: Likewise.
	* testsuite/21_strings/basic_string/cons/wchar_t/
	noexcept_move_construct.cc: Likewise.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/basic_string.h
    trunk/libstdc++-v3/include/bits/basic_string.tcc
    trunk/libstdc++-v3/testsuite/21_strings/basic_string/allocator/char/move_assign.cc
    trunk/libstdc++-v3/testsuite/21_strings/basic_string/allocator/wchar_t/move_assign.cc
    trunk/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/noexcept_move_construct.cc
    trunk/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/noexcept_move_construct.cc